The invention relates to a radiation measurement installation, comprising a radiation source, which emits a fan-shaped beam of rays, and a radiation receiver, which exhibits a series of photoelectric transducers before which a scintillation crystal arrangement is disposed.
A radiation measurement arrangement of this type is e.g. employed in a computer tomograph and serves the purpose of scanning a transverse layer of a radiography subject from different projections. A computer determines, from the output signals of the transducers at the various projections, the attenuation coefficients of image points arranged in a matrix. The computed attenuation coefficients can then be reproduced on a video unit as an image of the scanned transverse layer.
It is also known to scan a patient, who is lying between the radiation source and the radiation receiver, in that a relative movement in the longitudinal direction of a patient support takes place between said patient and the radiation measurement installation. In this manner, it is possible to construct an x-ray shadow image in line-by-line fashion.
In the case of radiation measurement installations of the type initially cited, it is known, for the purpose of influencing the spatial resolution in the longitudinal direction of the detector row forming the radiation receiver to provide adjustable diaphragms by means of which the effective length of a detector can be altered. In so doing, the x-ray quanta striking the diaphragm, however, do not contribute to the detector signal; but they do contribute to the dose which is supplied to the patient.